Add your beans to a quart container, then fill to the top with water and salt. Soak overnight.
Add your soaked beans with water to your sauce pot, then cover by 1.5" of water. Bring this to a heavy simmer, then reduce to low and cook until beans are soft and close to falling apart, about 30-45 minutes. When done, remove the beans from the water with a strainer. Keep the liquid, you'll need it later.
Mash your beans to desired consistency. I typically like my refried beans to have more texture, so I barely mash them at all. If you like a smoother refried bean, then you may want to put them into a blender to completely make them smooth. Once the beans are mashed to your preference, set aside.
Heat your pot over medium high heat, then add your oil to the pot. When it starts to shimmer, add in your onion. Cook until translucent.
Add in your taco blend seasoning, then cook until the spices have bloomed.
Add in your beans, then add a cup of the cooking liquid to the pot. Bring to a boil and cook for 15-20 minutes or until most of the cooking liquid has cooked out. Your final texture should be slightly thinner than you will want to eat them because they will thicken up after cooling.
